The LaF package provides methods for fast access to large ASCII files.
Currently the following file formats are supported:
* comma separated format (csv) and other separated formats and
* fixed width format.
It is assumed that the files are too large to fit into memory, although
the package can also be used to efficiently access files that do fit
into memory.
In order to process files that are too large to fit into memory, methods
are provided to access and process file blockwise. Furthermore, an
opened file can be indexed as one would a data.frame. In this way
subsets. or specific columns can be read into memory. For example,
assuming that an object laf has been created using one of the functions
laf_open_csv or laf_open_fwf, the third column from the file can be read
into memory using:
> col <- laf[,3]
The LaF-manual vignette contains a description of all functionality
provided:
http://laf-r.googlecode.com/files/LaF-manual_0.3.pdf
The Laf-benchmark vignette compares the performance of LaF to the
standard R-routines read.table and read.fwf:
http://laf-r.googlecode.com/files/LaF-benchmark_0.3.pdf